/*
  * USB Skeleton driver - 2.2
  *
  * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
  *
  *      This program is free software; you can redistribute it and/or
  *      modify it under the terms of the GNU General Public License as
  *      published by the Free Software Foundation, version 2.
  *
 * This driver is based on the 2.6.3 version of drivers/usb/usb-	skeleton.c
  * but has been rewritten to be easier to read and use.
  *
  */
 
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/kref.h>
 #include <linux/uaccess.h>
 #include <linux/usb.h>
 #include <linux/usb/ch9.h>
 #include <linux/mutex.h>
 
 
 /* Define these values to match your devices */
 #define USB_SKEL_VENDOR_ID      0x16C0
 #define USB_SKEL_PRODUCT_ID     0x06B3
 
 /* table of devices that work with this driver */
 static const struct usb_device_id skel_table[] = {
         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
         { }                                     /* Terminating entry */
 };
 MODULE_DEVICE_TABLE(usb, skel_table);
 
 
 /* Get a minor range for your devices from the usb maintainer */
#define USB_SKEL_MINOR_BASE     196
 
 /* our private defines. if this grows any larger, use your own .h file  */
 #define MAX_TRANSFER            (PAGE_SIZE - 512)
 /* MAX_TRANSFER is chosen so that the VM is not stressed by
    allocations > PAGE_SIZE and the number of packets in a page
    is an integer 512 is the largest possible packet on EHCI */
 #define WRITES_IN_FLIGHT        8
 /* arbitrarily chosen */
 
 /* Structure to hold all of our device specific stuff */
 struct usb_skel {
         struct usb_device       *udev;                  /* the usb device for this device */
         struct usb_interface    *interface;             /* the interface for this device */
         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
         struct usb_anchor       submitted;              /* in case we need to retract our submissions */
         struct urb              *bulk_in_urb;           /* the urb to read data with */
         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
         size_t                  bulk_in_size;           /* the size of the receive buffer */
         size_t                  bulk_in_filled;         /* number of bytes in the buffer */
         size_t                  bulk_in_copied;         /* already copied to user space */
         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
         int                     errors;                 /* the last request tanked */
         bool                    ongoing_read;           /* a read is going on */
         bool                    processed_urb;          /* indicates we haven't processed the urb */
         spinlock_t              err_lock;               /* lock for errors */
         struct kref             kref;
         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
         struct completion       bulk_in_completion;     /* to wait for an ongoing read */
};
 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
 
 static struct usb_driver usb2lpt_driver;
 static void skel_draw_down(struct usb_skel *dev);
 
 static void skel_delete(struct kref *kref)
 {
         struct usb_skel *dev = to_skel_dev(kref);
 
         usb_free_urb(dev->bulk_in_urb);
         usb_put_dev(dev->udev);
         kfree(dev->bulk_in_buffer);
         kfree(dev);
 }
  
 static int skel_open(struct inode *inode, struct file *file)
 {
          struct usb_skel *dev;
          struct usb_interface *interface;
          int subminor;
          int retval = 0;


 	 printk("no open");
  
          subminor = iminor(inode);
  
          interface = usb_find_interface(&usb2lpt_driver, subminor);
          if (!interface) {
                  err("%s - error, can't find device for minor %d",
                       __func__, subminor);
                  retval = -ENODEV;
                  goto exit;
         }
         
         dev = usb_get_intfdata(interface);
         if (!dev) {
                 retval = -ENODEV;
                 goto exit;
         }
         
        /* increment our usage count for the device */
         kref_get(&dev->kref);
 
         /* lock the device to allow correctly handling errors
          * in resumption */
         mutex_lock(&dev->io_mutex);
         
         retval = usb_autopm_get_interface(interface);
         if (retval)
                 goto exit;
         
         /* save our object in the file's private structure */
         file->private_data = dev;
         mutex_unlock(&dev->io_mutex);
         
exit:
         return retval;
}

 
static int skel_release(struct inode *inode, struct file *file)
{
         struct usb_skel *dev;
 
         dev = file->private_data;
         if (dev == NULL)
                 return -ENODEV;

         /* allow the device to be autosuspended */
         mutex_lock(&dev->io_mutex);
         if (dev->interface)
                 usb_autopm_put_interface(dev->interface);
         mutex_unlock(&dev->io_mutex);
 
         /* decrement the count on our device */
         kref_put(&dev->kref, skel_delete);
         return 0;
}
 
static int skel_flush(struct file *file, fl_owner_t id)
{
         struct usb_skel *dev;
         int res;
 
         dev = file->private_data;
         if (dev == NULL)
                 return -ENODEV;
 
         /* wait for io to stop */
         mutex_lock(&dev->io_mutex);
         skel_draw_down(dev);

         /* read out errors, leave subsequent opens a clean slate */
         spin_lock_irq(&dev->err_lock);
         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
         dev->errors = 0;
         spin_unlock_irq(&dev->err_lock);
 
         mutex_unlock(&dev->io_mutex);

         return res;
}
 
static void skel_read_bulk_callback(struct urb *urb)
{
        struct usb_skel *dev;
 
//printk( "\nno read callback 6\n");        
        dev = urb->context;
 
        spin_lock(&dev->err_lock);
        /* sync/async unlink faults aren't errors */
        if (urb->status) {
                 if (!(urb->status == -ENOENT ||
                     urb->status == -ECONNRESET ||
                     urb->status == -ESHUTDOWN))
                         err("%s - nonzero write bulk status received: %d",
                             __func__, urb->status);
 
                 dev->errors = urb->status;
         } else {
                 dev->bulk_in_filled = urb->actual_length;
         }
         dev->ongoing_read = 0;
         spin_unlock(&dev->err_lock);
 
         complete(&dev->bulk_in_completion);
}
 
static int skel_do_read_io(struct usb_skel *dev, size_t count)
{
         int rv;
 
//printk( "\nno read io 6\n");          
         /* prepare a read */
         usb_fill_bulk_urb(dev->bulk_in_urb,
                         dev->udev,
                         usb_rcvbulkpipe(dev->udev,
                                 dev->bulk_in_endpointAddr),
                         dev->bulk_in_buffer,
                         min(dev->bulk_in_size, count),
                         skel_read_bulk_callback,
                         dev);
         /* tell everybody to leave the URB alone */
         spin_lock_irq(&dev->err_lock);
         dev->ongoing_read = 1;
         spin_unlock_irq(&dev->err_lock);
 
         /* do it */
         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
         if (rv < 0) {
                 err("%s - failed submitting read urb, error %d",
                         __func__, rv);
                 dev->bulk_in_filled = 0;
                 rv = (rv == -ENOMEM) ? rv : -EIO;
                 spin_lock_irq(&dev->err_lock);
                 dev->ongoing_read = 0;
                 spin_unlock_irq(&dev->err_lock);
         }
 
         return rv;
 }
 
static ssize_t skel_read(struct file *file, char *buffer, size_t count,
                          loff_t *ppos)
{
         struct usb_skel *dev;
         int rv;
         bool ongoing_io;
 
         //printk( "\nno read\n");
         dev = file->private_data;
 
         /* if we cannot read at all, return EOF */
         if (!dev->bulk_in_urb || !count)
                 return 0;
 
         /* no concurrent readers */
         rv = mutex_lock_interruptible(&dev->io_mutex);
         if (rv < 0)
                 return rv;
 
         if (!dev->interface) {          /* disconnect() was called */
                 rv = -ENODEV;
                 goto exit;
         }
 
         /* if IO is under way, we must not touch things */
 retry:
         spin_lock_irq(&dev->err_lock);
         ongoing_io = dev->ongoing_read;
         spin_unlock_irq(&dev->err_lock);
 
//printk( "\nno read 3\n");         
         
         if (ongoing_io) {
                 /* nonblocking IO shall not wait */
                 if (file->f_flags & O_NONBLOCK) {
                         rv = -EAGAIN;
                         goto exit;
                 }
                 /*
                  * IO may take forever
                  * hence wait in an interruptible state
                  */
//printk( "\nno read 4\n");                  
                  
                 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
                 if (rv < 0)
                         goto exit;
                 /*
                  * by waiting we also semiprocessed the urb
                  * we must finish now
                  */
                 dev->bulk_in_copied = 0;
                 dev->processed_urb = 1;
         }

         if (!dev->processed_urb) {
                 /*
                  * the URB hasn't been processed
                  * do it now
                  */
//printk( "\nno read 5\n");                  
                 rv = skel_do_read_io(dev, count);
                 if (rv < 0)
                         goto exit;
//printk( "\nno read 5.1\n");                 
                  
                 wait_for_completion(&dev->bulk_in_completion);
                 dev->bulk_in_copied = 0;
                 dev->processed_urb = 1;
         }
 
         /* errors must be reported */
         rv = dev->errors;
         if (rv < 0) {
                 /* any error is reported once */
                 dev->errors = 0;
                 /* to preserve notifications about reset */
                 rv = (rv == -EPIPE) ? rv : -EIO;
                 /* no data to deliver */
                 dev->bulk_in_filled = 0;
                 /* report it */
                 goto exit;
         }
 //printk( "\nno read 61\n"); 
         /*
          * if the buffer is filled we may satisfy the read
          * else we need to start IO
          */
 
         if (dev->bulk_in_filled) {
                 /* we had read data */
                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
                 size_t chunk = min(available, count);

//printk( "\nno read 62\n");          	 
                 
                 if (!available) {
                         /*
                          * all data has been used
                          * actual IO needs to be done
                          */
                         rv = skel_do_read_io(dev, count);
                         if (rv < 0)
                                 goto exit;
                         else
                                 goto retry;
                 }
                 /*
                  * data is available
                  * chunk tells us how much shall be copied
                  */
 
                 if (copy_to_user(buffer,
                                  dev->bulk_in_buffer + dev->bulk_in_copied,
                                  chunk))
                         rv = -EFAULT;
                 else
                         rv = chunk;
 
                 dev->bulk_in_copied += chunk;
 
                 /*
                  * if we are asked for more than we have,
                  * we start IO but don't wait
                  */
                 if (available < count)
                         skel_do_read_io(dev, count - chunk);
         } else {
//printk( "\nno read 6\n");         	 
         	 
                 /* no data in the buffer */
                 rv = skel_do_read_io(dev, count);
                 if (rv < 0)
                         goto exit;
                 else if (!(file->f_flags & O_NONBLOCK))
                         goto retry;
                 rv = -EAGAIN;
         }
 exit:
         mutex_unlock(&dev->io_mutex);
//printk( "\nno read 6666\n");          
         return rv;
}
 
static void skel_write_bulk_callback(struct urb *urb)
{
         struct usb_skel *dev;
 
         dev = urb->context;
 
         /* sync/async unlink faults aren't errors */
         if (urb->status) {
                 if (!(urb->status == -ENOENT ||
                     urb->status == -ECONNRESET ||
                     urb->status == -ESHUTDOWN))
                         err("%s - nonzero write bulk status received: %d",
                             __func__, urb->status);
 
                 spin_lock(&dev->err_lock);
                 dev->errors = urb->status;
                 spin_unlock(&dev->err_lock);
         }
 
         /* free up our allocated buffer */
         usb_free_coherent(urb->dev, urb->transfer_buffer_length,
                           urb->transfer_buffer, urb->transfer_dma);
         up(&dev->limit_sem);
 }
 
static ssize_t skel_write(struct file *file, const char *user_buffer,
                           size_t count, loff_t *ppos)
{
         struct usb_skel *dev;
         int retval = 0;
         struct urb *urb = NULL;
         char *buf = NULL;
         size_t writesize;

	 //printk( "\nno write\n");
	 
	 writesize = min(count, (size_t)MAX_TRANSFER);
         dev = file->private_data;
 
         /* verify that we actually have some data to write */
         if (count == 0)
                 goto exit;
 
         /*
          * limit the number of URBs in flight to stop a user from using up all
          * RAM
          */
         if (!(file->f_flags & O_NONBLOCK)) {
                 if (down_interruptible(&dev->limit_sem)) {
                         retval = -ERESTARTSYS;
                         goto exit;
                 }
         } else {
                 if (down_trylock(&dev->limit_sem)) {
                         retval = -EAGAIN;
                         goto exit;
                 }
         }
 
         spin_lock_irq(&dev->err_lock);
         retval = dev->errors;
         if (retval < 0) {
                 /* any error is reported once */
                 dev->errors = 0;
                 /* to preserve notifications about reset */
                 retval = (retval == -EPIPE) ? retval : -EIO;
         }
         spin_unlock_irq(&dev->err_lock);
         if (retval < 0)
                 goto error;
 
         /* create a urb, and a buffer for it, and copy the data to the urb */
         urb = usb_alloc_urb(0, GFP_KERNEL);
         if (!urb) {
                 retval = -ENOMEM;
                 goto error;
         }
 
         buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
                                  &urb->transfer_dma);
         if (!buf) {
                 retval = -ENOMEM;
                 goto error;
         }
 
         if (copy_from_user(buf, user_buffer, writesize)) {
                 retval = -EFAULT;
                 goto error;
         }
 
         /* this lock makes sure we don't submit URBs to gone devices */
         mutex_lock(&dev->io_mutex);
         if (!dev->interface) {          /* disconnect() was called */
                 mutex_unlock(&dev->io_mutex);
                 retval = -ENODEV;
                 goto error;
         }
 
         /* initialize the urb properly */
         usb_fill_bulk_urb(urb, dev->udev,
                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
                           buf, writesize, skel_write_bulk_callback, dev);
         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
         usb_anchor_urb(urb, &dev->submitted);
 
         /* send the data out the bulk port */
         retval = usb_submit_urb(urb, GFP_KERNEL);
         mutex_unlock(&dev->io_mutex);
         if (retval) {
                 err("%s - failed submitting write urb, error %d", __func__,
                     retval);
                 goto error_unanchor;
         }
 
         /*
          * release our reference to this urb, the USB core will eventually free
          * it entirely
          */
         usb_free_urb(urb);
 
 
         return writesize;
 
 error_unanchor:
         usb_unanchor_urb(urb);
 error:
         if (urb) {
                 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
                 usb_free_urb(urb);
         }
         up(&dev->limit_sem);
 
 exit:
         return retval;
 }
 
 static const struct file_operations skel_fops = {
         .owner =        THIS_MODULE,
         .read =         skel_read,
         .write =        skel_write,
         .open =         skel_open,
         .release =      skel_release,
         .flush =        skel_flush,
         .llseek =       noop_llseek,
 };
 
 /*
  * usb class driver info in order to get a minor number from the usb core,
  * and to have the device registered with the driver core
  */
 static struct usb_class_driver skel_class = {
         .name =         "musb2lpt",
         .fops =         &skel_fops,
         .minor_base =   USB_SKEL_MINOR_BASE,
 };
 
//int usb_endpoint_maxp(struct usb_endpoint_descriptor *endpoint);
 
 static int skel_probe(struct usb_interface *interface,
                       const struct usb_device_id *id)
 {
         struct usb_skel *dev;
         struct usb_host_interface *iface_desc;
         struct usb_endpoint_descriptor *endpoint;
         size_t buffer_size;
         int i;
         int retval = -ENOMEM;

	 printk("<1> Here probe %X %X\n", id ->idVendor, id->idProduct);
         /* allocate memory for our device state and initialize it */
         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
         if (!dev) {
                 err("Out of memory");
                 goto error;
         }
         kref_init(&dev->kref);
         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
         mutex_init(&dev->io_mutex);
         spin_lock_init(&dev->err_lock);
         init_usb_anchor(&dev->submitted);
         init_completion(&dev->bulk_in_completion);
 
         dev->udev = usb_get_dev(interface_to_usbdev(interface));
         dev->interface = interface;
 
         /* set up the endpoint information */
         /* use only the first bulk-in and bulk-out endpoints */
         iface_desc = interface->cur_altsetting;
	 printk("inumber = %d, endpoints = %d", iface_desc->desc.bInterfaceNumber, iface_desc->desc.bNumEndpoints);
	 if (iface_desc->desc.bInterfaceNumber > 0)  {
            //usb_set_intfdata(interface, dev);
	    return ENOMEM;
	    goto skip_endpoints;
	 }
      
         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                 endpoint = &iface_desc->endpoint[i].desc;
 
                 if (!dev->bulk_in_endpointAddr &&
                     usb_endpoint_is_bulk_in(endpoint)) {
                         /* we found a bulk in endpoint */
		   //printk("found an in endpoint");
                         buffer_size = usb_endpoint_maxp(endpoint);
                         dev->bulk_in_size = buffer_size;
                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
                         if (!dev->bulk_in_buffer) {
                                 err("Could not allocate bulk_in_buffer");
                                 goto error;
                         }
                         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
                         if (!dev->bulk_in_urb) {
                                 err("Could not allocate bulk_in_urb");
                                 goto error;
                         }
                 }
 
                 if (!dev->bulk_out_endpointAddr &&
                     usb_endpoint_is_bulk_out(endpoint)) {
                         /* we found a bulk out endpoint */
		   printk("found an out endpoint");
                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
                 }
         }
         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
                 err("Could not find both bulk-in and bulk-out endpoints");
                 goto error;
         }
 
 skip_endpoints:
         /* save our data pointer in this interface device */
         usb_set_intfdata(interface, dev);
 
         /* we can register the device now, as it is ready */
         retval = usb_register_dev(interface, &skel_class);
         if (retval) {
                 /* something prevented us from registering this driver */
                 err("Not able to get a minor for this device.");
                 usb_set_intfdata(interface, NULL);
                 goto error;
         }
 
         /* let the user know what node this device is now attached to */
         dev_info(&interface->dev,
                  "USB Skeleton device now attached to USBSkel-%d",
                  interface->minor);
         
         return 0;
 
 error:
         if (dev)
                 /* this frees allocated memory */
                 kref_put(&dev->kref, skel_delete);
         return retval;
 }
 
 static void skel_disconnect(struct usb_interface *interface)
 {
         struct usb_skel *dev;
         int minor = interface->minor;
 
         dev = usb_get_intfdata(interface);
         usb_set_intfdata(interface, NULL);
 
         /* give back our minor */
         usb_deregister_dev(interface, &skel_class);
 
         /* prevent more I/O from starting */
         mutex_lock(&dev->io_mutex);
         dev->interface = NULL;
         mutex_unlock(&dev->io_mutex);
 
         usb_kill_anchored_urbs(&dev->submitted);
 
         /* decrement our usage count */
         kref_put(&dev->kref, skel_delete);
 
         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 }
 
 static void skel_draw_down(struct usb_skel *dev)
 {
         int time;
 
         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
         if (!time)
                 usb_kill_anchored_urbs(&dev->submitted);
         usb_kill_urb(dev->bulk_in_urb);
 }
 
 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 {
         struct usb_skel *dev = usb_get_intfdata(intf);
 
         if (!dev)
                 return 0;
         skel_draw_down(dev);
         return 0;
 }
 
 static int skel_resume(struct usb_interface *intf)
 {
         return 0;
 }
 
 static int skel_pre_reset(struct usb_interface *intf)
 {
         struct usb_skel *dev = usb_get_intfdata(intf);
 
         mutex_lock(&dev->io_mutex);
         skel_draw_down(dev);
 
         return 0;
 }
 
 static int skel_post_reset(struct usb_interface *intf)
 {
         struct usb_skel *dev = usb_get_intfdata(intf);
 
         /* we are sure no URBs are active - no locking needed */
         dev->errors = -EPIPE;
         mutex_unlock(&dev->io_mutex);
 
         return 0;
 }
 
 static struct usb_driver usb2lpt_driver = {
         .name =         "musb2lpt",
         .probe =        skel_probe,
         .disconnect =   skel_disconnect,
         .suspend =      skel_suspend,
         .resume =       skel_resume,
         .pre_reset =    skel_pre_reset,
         .post_reset =   skel_post_reset,
         .id_table =     skel_table,
         .supports_autosuspend = 1,
 };
 
 module_usb_driver(usb2lpt_driver);
 
 MODULE_LICENSE("GPL");
 
#define DRIVER_VERSION "1"
#define DRIVER_DESC "UsbLpt"

static int __init mod_init(void)
{
        int retval;
 
         dbg("%s", __func__);
         retval = usb_register(&usb2lpt_driver);
         if (retval)
                 goto failed_sio_register;
 
         printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
                DRIVER_DESC "\n");
         return 0;
failed_sio_register:
         return retval;
}
 
static void __exit mod_exit(void)
{
        dbg("%s", __func__);

        usb_deregister(&usb2lpt_driver);
}

module_init(mod_init);
module_exit(mod_exit);


